In the oilfield industry, gas flaring or gas-liquid flaring remains a commonly used approach for handling of waste fluids produced in exploration wells or during well testing operations, since transportation of oil-contaminant waste from remote well-sites may be prohibitively expansive (for example, this situation is typical for offshore well testing). Progress has been achieved in the designing of gas flare apparatuses for gas combustion, and in the designing of multiphase flare apparatuses for fluid flows which include water, oil, gas condensate, and natural gas. However, evaluating performance of these flare apparatuses remains difficult, with well testing operators left to using indirect evidence, such as the absence of black smoke in the flame (which is an indicator of proper fuel/oxygen ratio in the flaring mixture and absence of soot) or relatively small amount of oily film on sea surface (which is an indicator of low fallout of oil droplets).
Conventional tools for the monitoring of combustion inefficiency are not applicable for open-atmosphere flare apparatuses. For open-air flare apparatuses, such as gas flare and liquid-gas flare apparatuses, the operation is complicated by external factors. For example, the content of waste fluid is unpredictable for some wells, and the completeness of fuel combustion depends on a variety of factors, such as the burner design, the fuel droplet size entering the flame, the fuel flow rate, and the atmospheric conditions for flame (such as wind strength and direction). The main outlet products of fuel combustion for this situation are carbon dioxide and water vapor (for the case of combustion of hydrocarbons), gaseous unburned products like CO, NOx, light alkanes and their derivatives, sulfur oxides, soot particles, droplets of water, and droplets of oil. Thus, it is desirable to have a method for estimating the fallout of liquid droplets around an open-air fuel burner in the nearest vicinity.